KLRC4 and systemic lupus erythematosus: At the single-cell level of TWAS using the panels from the California Lupus Epidemiology Study (CLUE) consortium, there was no significant association that passed the multiple testing correction threshold (FDR < 0.05); however, MTMR9 and killer-cell lectin-like receptor C4 (KLRC4) showed marginal significance (0.05 < FDR < 0.1) in CD8+ T-cell and natural killer cell (NK cell), respectively (Supplementary Table S2).